The extension of Abbey Green North pit by 75 ha is located on previously mined land within the approved development consent boundary.

The approval comes after Rio Tinto chief executive Tom Albanese warned that its proposed $2 billion Mt Pleasant mine in the Hunter Valley was in doubt because of high costs and government regulation and the state government released its draft strategic regional land use policy.

Run of mine coal would be extracted from the previously unmined Warkworth, Bowfield and Mount Arthur coal seams then hauled to the Mount Thorley coal preparation plants for processing before being loaded onto trains at the adjacent Mount Thorley coal loader and then railed to the Port of Newcastle to be exported.

Mt Thorley also proposes to use the final voids of the Abbey Green North and Abbey Green South pits to temporarily store mine water for use at the Mt Thorley Warkworth complex.

When future tailings storage is required, the pit voids would be dewatered and used for storage of tailings from both Mount Thorley and Warkworth mines.

This would improve MTW’s ability to manage its water balance in the short term and tailings storage in the long term.

Mt Thorley will realign a section of haul road to allow for the extended mining footprint and to enable continued coal haulage to the Mount Thorley CPP.

Mining of the proposed extension area would remove approximately 37 million bank cubic metres of overburden, some of which would be used in construction of the haul road. The majority of overburden would be placed around the east and west embankments of the existing MTO operations dam.

Modifications to MTO’s existing water management system would be required to accommodate the extension of mining and the proposed haul road realignment.

MTO will enlarge an existing process water dam and construct two small sediment dams. Other infrastructure to be relocated within the approved mine site includes water and tailings pipes, water truck fill points, lighting plants, tyre storage and a light vehicle wash bay.

The modification would not alter the approved mining extraction rate, mine life, mining methods, operating hours, equipment use or employment at the mine.

Mount Thorley mine was previously regulated under three development consents.

In order to simplify regulation of the mine, the department recommended that the older development consents (dating to 1981 and 1983) are surrendered as part of this modification.

Together, the Mt Thorley and Warkworth mines have approval to extract up to 28Mtpa of ROM coal, process this coal at either the Mount Thorley or Warkworth coal preparation plants and then rail it to export markets via the Mount Thorley coal loader.

A major extension of mining at Warkworth mine was approved by the Planning Assessment Commission on February 3. The Warkworth extension project expands open cut mining by 750ha to the west and extends the life of the mine by a further 11 years, until 2033.